If you get this error
Fatal error: Uncaught TypeError: in_array(): Argument #2 ($haystack) must be of type array, false given in /var/www/html/ubbthreads/libs/user.inc.php:608 Stack trace: #0 /var/www/html/ubbthreads/libs/user.inc.php(608): in_array() #1 /var/www/html/ubbthreads/scripts/addpost.inc.php(668): user->check_group_join() #2 /var/www/html/ubbthreads/ubbthreads.php(286): page_addpost_run() #3 {main} thrown in /var/www/html/ubbthreads/libs/user.inc.php on line 608
when posting or replying, delete all the stovebolt data from your browser. (Usually under Privacy in Settings). You'll be logged out. When you log back in, it should work properly.
